The use of furnace modules and evaporator modules in home heating systems is well known. Typically, but not necessarily, assemblies incorporating these modules are located in an attic. Installation of prior art assemblies is normally accomplished in situ at the job site, the modules typically being fixedly connected together by sheet metal transitions custom fabricated from sheet metal and attached by screws. These transition structures are required to adapt the modules to one another since adjacent modules often employ different sized and/or shaped air flow openings. Sealants are usually employed to provide some semblance of air-tight connection.
This prior art approach is time consuming and typically must be carried out by highly trained personnel, further adding to cost of a project. Inconsistent results are obtained. Such installations, due to their more or less permanent character make it difficult to replace parts and components. They are also relatively long, causing installation problems.